1. Field of the Art
This invention relates to power transmission chains and, more particularly, to chains and chain belts used with continuously variable transmissions or variable-pulley transmissions.
2. Discussion of the Related Art
Chains or chain belts are conventionally utilized in power transmission applications, such as the transmission of power in automotive transmissions, engine timing applications, or industrial power transmission applications. Such chain-belts are also utilized in vehicle transmissions of the type known as variable-pulley or continuously variable transmissions (CVTs). A CVT typically includes a pair of pulleys of variable or adjustable effective diameter that are placed on a pair of spaced shafts. An endless chain or loop connects the pulleys to transmit power between the shafts.
One type of an endless chain belt placed across variable diameter pulleys for power transmission is one which has a first chain and a second chain, or a pair of chain portions, with a plurality of interleaved, long-plate shaped link plates connected by rocker pins. The two chains are interconnected in a parallel, but longitudinally offset or phased relationship. Each rocker pin consists of a first pin and a second pin that rock along mutually contacting surfaces. The rocker pins extend through respective pin-fitting apertures or holes formed through longitudinally opposite end portions of each link plate, to thereby connect the adjacent sets of link plates. Load block members, also known as struts or belt blocks, are placed at a predetermined interval or spacing along the length of the first and second chains for the transmission of load or power, such that each load block extends in the direction of width of the chain belt. The load blocks are associated with the inner side of the first and second chains, and have a length substantially equal to the total width of the two side-by-side chains. The load blocks are pinch-pressed between the opposed surfaces of the V-shaped groove of each variable-diameter pulley and are associated alternately with the first and second chains.
An example of such a chain belt is disclosed in Publication No. 1-136747 (published in 1989) of unexamined Japanese Utility Model Application. In such a known chain belt, the tip of each rocker pin of one of the first and second chains extends through this one chain toward the side of the other chain in the transverse or width direction of the chain belt. Position-regulating means in the form of an annular member or ring member is fitted on the tip of each rocker pin of one chain, such that the ring member is located between the facing sides of the two chains, so that the ring member controls the relative lengthwise position or inhibits the relative movement of the two chains, through the contact of the circumferential surface of the ring member and the tips of of the rocker pins of the other chain.
In the conventional chain belt of this type, however, both of the first and second pins of the rocker pin are received at their tips in the bore of the ring member. In this arrangement, relative sliding occurs between the tips of the first and second pins and the surface of the bore of the ring member when the two pins roll relative to each other on their contacting surfaces during movement of the chain belt around the pulleys. This relative sliding motion causes wear on the rocker pins and the ring members, and power loss or reduction of the power transmission capacity of the chain.